for example, there is an option:
Min Static File Size (bytes):default is 300

mean if file size of .css etc less than 300 bytes, then no gzip.

Click to expand...

Oh I was aware of that the style I'm trying to reach is about 88K so it should be compressed, the min and max values are 300B / 1M so I'm still unsure what could be this issue, thanks for the quick response NiteWave.

If Auto Update Static is set to Yes, check Static GZIP Cache Directory (default to swap directory /tmp/lshttpd/swap if Static GZIP Cache Directory field is empty) and make sure it is writeable by web server user _and_ it is not full.

Oh my bad, Auto update static was activated and it is saving now on the Swap directory, I got a little confused about the static gzip cache directory which is pretty much by default swap dir unless specified.